Created a tool to remove duplicate includes between h and cc files.

BUG=

Review-Url: https://codereview.chromium.org/2379993006
Cr-Commit-Position: refs/heads/master@{#423018}

tools/remove_duplicate_includes.py

+#!/usr/bin/env python
+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""This script will search through the target folder specified and try to find
+duplicate includes from h and cc files, and remove them from the cc files. The
+current/working directory needs to be chromium_checkout/src/ when this tool is
+run.
+
+Usage: remove_duplicate_includes.py --dry-run components/foo components/bar
+"""
+
+import argparse
+import collections
+import logging
+import os
+import re
+import sys
+
+# This could be generalized if desired, and moved to command line arguments.
+H_FILE_SUFFIX = '.h'
+CC_FILE_SUFFIX = '.cc'
+
+# The \s should allow us to ignore any whitespace and only focus on the group
+# captured when comparing between files.
+INCLUDE_REGEX = re.compile('^\s*(#include\s+[\"<](.*?)[\">])\s*$')
+
+def HasSuffix(file_name, suffix):
+  return os.path.splitext(file_name)[1] == suffix
+
+def IsEmpty(line):
+  return not line.strip()
+
+def FindIncludeSet(input_lines, h_path_to_include_set, cc_file_name):
+  """Finds and returns the corresponding include set for the given .cc file.
+
+  This is done by finding the first include in the file and then trying to look
+  up an .h file in the passed in map. If not present, then None is returned
+  immediately.
+  """
+  for line in input_lines:
+    match = INCLUDE_REGEX.search(line)
+    # The first include match should be the corresponding .h file, else skip.
+    if match:
+      h_file_path = os.path.join(os.getcwd(), match.group(2))
+      if h_file_path not in h_path_to_include_set:
+        print 'First include did not match to a known .h file, skipping ' + \
+          cc_file_name + ', line: ' + match.group(1)
+        return None
+      return h_path_to_include_set[h_file_path]
+
+def WithoutDuplicates(input_lines, include_set, cc_file_name):
+  """Checks every input line and sees if we can remove it based on the contents
+  of the given include set.
+
+  Returns what the new contents of the file should be.
+  """
+  output_lines = []
+  # When a section of includes are completely removed, we want to remove the
+  # trailing empty as well.
+  lastCopiedLineWasEmpty = False
+  lastLineWasOmitted = False
+  for line in input_lines:
+      match = INCLUDE_REGEX.search(line)
+      if match and match.group(2) in include_set:
+        print 'Removed ' + match.group(1) + ' from ' + cc_file_name
+        lastLineWasOmitted = True
+      elif lastCopiedLineWasEmpty and lastLineWasOmitted and IsEmpty(line):
+        print 'Removed empty line from ' + cc_file_name
+        lastLineWasOmitted = True
+      else:
+        lastCopiedLineWasEmpty = IsEmpty(line)
+        lastLineWasOmitted = False
+        output_lines.append(line)
+  return output_lines
+
+def main():
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--dry-run', action='store_true',
+    help='Does not actually remove lines when specified.')
+  parser.add_argument('targets', nargs='+',
+    help='Relative path to folders to search for duplicate includes in.')
+  args = parser.parse_args()
+
+  # A map of header file paths to the includes they contain.
+  h_path_to_include_set = {}
+
+  # Simply collects the path of all cc files present.
+  cc_file_path_set = set()
+
+  for relative_root in args.targets:
+    absolute_root = os.path.join(os.getcwd(), relative_root)
+    for dir_path, dir_name_list, file_name_list in os.walk(absolute_root):
+      for file_name in file_name_list:
+        file_path = os.path.join(dir_path, file_name)
+        if HasSuffix(file_name, H_FILE_SUFFIX):
+          # By manually adding the set instead of using defaultdict we can avoid
+          # warning about missing .h files when the .h file has no includes.
+          h_path_to_include_set[file_path] = set()
+          with open(file_path) as fh:
+            for line in fh:
+              match = INCLUDE_REGEX.search(line)
+              if match:
+                h_path_to_include_set[file_path].add(match.group(2))
+        elif HasSuffix(file_name, CC_FILE_SUFFIX):
+          cc_file_path_set.add(file_path)
+
+  for cc_file_path in cc_file_path_set:
+    cc_file_name = os.path.basename(cc_file_path)
+    with open(cc_file_path, 'r' if args.dry_run else 'r+') as fh:
+      # Read out all lines and reset file position to allow overwriting.
+      input_lines = fh.readlines()
+      fh.seek(0)
+      include_set = FindIncludeSet(input_lines, h_path_to_include_set,
+                                   cc_file_name)
+      if include_set:
+        output_lines = WithoutDuplicates(input_lines, include_set, cc_file_name)
+        if not args.dry_run:
+          fh.writelines(output_lines)
+          fh.truncate()
+
+if __name__ == '__main__':
+  sys.exit(main())